MOTORCROSS re-poweri/mods. your project advice welcome!

[ghostrider]

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Hi guys!
I started this thread for anyone interested in repowering thier motorcross bikes.
I realise parts can be expensive and hard to get so a common idea is to repower your old bike with another motor.

My project at the moment is a tsr125 I am converting to a 250cc 4 stroke.

I just started the project last night, so its still in its infant stage...
I still dont know if ill complete the project as Im desperately trying to buy a friends cr125 (with a guba motor). I would love to fit the 250cc engine to it.

anyway ill proceed in the following posts about what im up to...

[ghostrider]

heres a picture of the bike with both engines ready for the swap...

[ghostrider]

the first rusi bike i bought for the donor engine wasnt much good it had crank bearings that needed replacing so i bought another one with a good engine and heaps of spare parts i could use for my wifes xrm...

[ghostrider]

so why bother doing this?
The 2 stroke engine is in great condition, its a 6 speed and I have just installed a new piston and rings...
but being a 2stroke its not a fuel-efficient bike, it sounds 'tinny' and lacks power for climbing hills in the mountains with my wife and 2yr old son on it.

the 250cc engine was given to me by a friend. all it owes me is postage getting it here and a hand full of parts. maybe all up it will owe me about 3-4k. I could sell the old 2stroke engne to recover the costs.
the actual bike only owes me 10k. It has or/cr but is out of date for some time now.

other mods?
well, i plan on putting a longer rear shock on it and replacing the plastics and tank with one of the crf type conversions available in cebu. this is just an idea at the moment and may not be an option as the 'kit' costs about 7k all up.

the next step would be to replace the front forks with a set off a xt250 yamaha as they are a little bigger.

im really impressed with the 'link' rear shock set up on the tsr. it has a real comfortable ride and all the electrics are in excellent condition. It has a battery and good headlight and will be easy to fit the zonshen engine to the existing system...

[ghostrider]

so today ill ride up to see my friend and offer him some money for his cr125. if he accepts ill start on the cr/zongshen conversion.
if not ill continue with the tsr conversion.

in all reality i think the tsr is a better option as i really wanted the project more for road/trail rather than for MX.

another thing to do then with the spare tsr motor would be to fit it to the cr frame, but i think it would lack speed as origional cr engine is an absolute powerhouse compared to the tsr!

any suggestions guys?

[zemville]

sir, you are from bohol right??

i think, mas powerful and engine sa CR125 compared to TSR125 coz the engine of cr is built for MX. you said that the engine of the CR125 is broken?? i think it's much better to fit your Zongshen engine in the TSR125 chasis and then the TSR125 engine on the CR chasis.

IMHO sir.. i am not an expert sad

[ghostrider]

yeah youre right bro. I started today and I yhink the tsr would be a better bike for the 250.
It would feel too slow in a cr frame!

also If the tsr doesnt handle the dirt too well i could always motard it for the road!

[zemville]

you just need about 10-20k for a good motard set-up.. where are you located in bohol bro?? i am from bohol

[jack_sparrow]

up ko ni beh...

[ghostrider]

im in tubigon bro,
great riding tracks here.

im having hassles with some of my pictures uploading but ill try again now...